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jim hardy
#5
Mar9-12, 02:28 PM
Sci Advisor
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you should be okay with what you described.

suffice it to say
the wires should be in contact at the sensing end
and be connected to a high impedance voltmeter at the measuring end.
Microvolts you read at meter are in proportion to temperature difference between ends. So you need a thermometer alongside your voltmeter.

http://www.omega.com/thermocouples.html

Basically a wire that has a temperature gradient along it also has a small potential gradient.
Since the two wires are of different metals their voltage gradients are unequal so at measuring end you sense a potential difference .

Try it on your workbench.
Connect a piece or thermocouple extension wire to your voltmeter, twist end together and observe ~ zero.
Then place an ice cube on end, then heat it with a match and observe opposite polarities.